Stern drive engine mount

ABSTRACT

A three point mounting system for the engine of a marine inboard-outboard stern drive unit. Bi-axially adjustable side mounts support the weight of the engine and an elastomeric sealing element around the drive shaft housing is radially expanded within a cylindrical passage through the transom to steady the engine in the region immediately adjacent the Ujoint.

Tluit tates Mat Haas]! 1 STERN DRIVE ENGINE MOUNT Feb. H, 1975 3,259,099 7/1966 Keikhuefer 115/34 R 3,529,564 9/1970 Osswald 115/34 R Primary Examiner-Trygve M. Blix Assistant ExaminerSherman D. lBasinger Attorney, Agent, or FirmWi1liam G. Lawler, Jr.

[5 7] ABSTRACT A three point mounting system for the engine of a marine inboard-outboard stern drive unit. Bi-axially adjustable side mounts support the weight of the engine and an elastomeric sealing element around the drive shaft housing is radially expanded within a cylindrical passage through the transom to steady the engine in the region immediately adjacent the U-joint.

5 Claims, 4 Drawing Figures PATENTED FEB-1 1 I975 SHEET 1 OF 2 fill. 1 m 4 SHEET 2 BF 2 PATENTED FEB] l 8975 srEEN DRIVE ENGINE MOUNT BACKGROUND OF THE INVENTION DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 11 illustrates an inboard-outboard marine pro- Inboard-outboard for stern drive marine propulsion 5 PulSion Unit ud ng n engine I and an outboard units generally of the type illustrated in FIG. 1 are well known to the art. These units employ a double cardan universal joint to couple the outboard drive shaft to the inboard engine drive shaft. This permits the outboard unit to be tilted upwardly about a horizontal axis through the U-joint assembly, and to be simultaneously turned about a vertical axis through the U-joint assembly.

The double U-joint assembly inherently produces two force pulses per revolution; which pulses increase in magnitude with the degree of angular displacement of the outboard drive assembly from the axis of the engine drive shaft. Experience has indicated that moderate to severe vibrations can result when the unit is put into a hard turn at high power, which vibrations are both annoying and destructive.

It is an object of the invention to reduce vibration by steadying the engine drive shaft as close as possible to point of their generation.

It is another objective of the invention to provide a transom seal around the engine drive shaft housing which will prevent entry of water into the boat in the event that the outdrive unit is broken away.

SUMMARY OF THE PRESENT INVENTION Basically the invention comprises a threepoint engine mounting system including bi-axially adjustable engine side mounts, a single point stern mount comprising a radially expandable elastomeric element positioned around a drive shaft housing and means associated with the drive shaft housing for expanding the elastomeric element radially into contact with the inner walls of a cylindrical passage through the transom plate.

A primary advantage of the invention is the simplicity and utility with which the aforementioned objectives are achieved.

Another advantage of the invention is that it provides for, and permits adjustment of, axial positioning of the engine.

A further advantage of the invention is that it provides positive radial alignment of the engine drive shaft at the point of the rear mounting.

Other objectives, advantages, and various further features of novelty and invention will be pointed out or will occur to those skilled in the art from a reading of the following specification in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cut-away side elevation of an engine and associated stern drive unit as installed in a boat.

FIG. 2 is a cross-sectional view of a side engine mount taken along line 2-2 of FIG. 1.

FIG. 3 is a cut-away side view of the single point rear engine mount of the invention.

FIG. 4 is a rear end view of the single point engine mount of the invention taken along line 4-4 of FIG. 3.

stern drive 2. The engine is supported on each side by r a side engine mount 3, such as illustrated in FIG. 2, and at the rear by the annularly expanding mount of the invention' 4. As known to the art, the outboard drive housing 5 is secured to the transom 6 of the boat by bolts such as 7 which extend through the transom and engage an inboard transom plate 3.

In the invention, a drive shaft housing 9 extends rearwardly on the engine I into a cylindrical channel ll through the transom 6.

FIG. 2 illustrates a bi-axially adjustable engine mount of a type known to the art. The base 15 of the mount is secured to appropriate structural members of the boat hull while the adjustable member 16 is bolted to the side of the engine 1. The base units 15 are spaced laterally sufficiently to permit lateral alignment of the engine through the sliding of the adjustable element 16 upon a supporting cylinder 17 passing therethrough. Once positioned, means are provided to lock element 16 in the selected position upon the supporting bar 17. The engine may then be adjusted vertically by use of the retaining bolts 18 of the mounting units in a manner known to the art. I

Referring now to FIG. 3, the novel mounting unit of the invention comprises a drive shaft housing 9 secured to the engine transmission cover 10 by bolts such as 12. An annular step 23 in the outer wall 24 of the housing 9 provides a seat for an annular elastomeric mounting element 25. An annular locking collar 26 attaches to the outer end of the housing 9 and functions as illustrated to retain a bearing 22 in an annular seat 20 cut into the inner wall 21 of the housing 9, and to axially compress the elastomeric mounting element 25 against its seat 23. The housing 9 is retained in place by a series of nuts 27 which thread onto studs 28 seated in the housing 9.

Upon installation the drive shaft housing 9, with the bearing 22, the elastomeric element 25 and the locking collar 26 attached, is inserted into the cylindrical passage 11 as illustrated in FIG. 1. Passage 11 may be provided by a structural element 31 of the stern drive housing 5 extending through the transom 6 of the boat. Alternatively, the cylindrical passage ll could be provided by structure associated with the transom plate 8.

Element 31 includes a radial shoulder 32 which extends inwardly into the cylindrical passage 11 and serves to position the engine and drive shaft in fore and aft position for connection to the double U-joint. With the collar 26 pre-positioned by the relaxed elastomeric element 25, the engine is moved aft until the collar 26 abuts the shoulder 32 and the engine is thereby properly positioned fore and aft. The nuts 27 are then gradually and equally tightened. As the nuts 27 are tightened, an inner annular portion 34 of the collar 26 engages the outside of the housing 35 of the bearing 22, and annular portion 37 extending axially of the collar 26 compresses the elastomeric element 25 against the step 23 in the drive shaft housing 9. The nuts 27 are tightened until the collar 26 is seated against the bearing housing 35, securing the bearing and causing the elastomeric element 25 to expand radially into interior of the contact with cylindrical channel 11. At this point the bearing 22 will be securely seated between the shoulder 34 on the collar 26 and the step in the drive shaft housing, and the elastomeric element 25 will have been expanded by compression between the annular element 37 of the collar 26 and the step 23 in the drive shaft housing to center and frictionally lock the drive shaft housing 9 within the channel 11.

It is significant to note that the position of the drive shaft housing 9 may be locked by friction as described at any position within the channel 11- by merely tightening of the collar 26. This feature of the invention provides an added dimension in engine alignment which may be utilized if desired; although it is anticipated that the engine will be positioned by the abutment of ring 26 against the shoulder 32 as described above.

Finally, referring to FIG. 4, the collar 26 may be retained by six nuts 27 equally spaced about its circumference, and should include a grease fitting and necessary channeling (not shown) through which the bearing 22 may be lubricated.

The driving shaft 19 of U-joint assembly is splined to the output shaft 39 of transmission and is normally a part of the outdrive assembly, which is installed after the engine has been mounted. Upon installation, the engine is first positioned fore and aft as described, the side mounts 3 fastened to the stringers in the boat hull, and then the collar 26 is tightened. The engine drive shaft may then be finally aligned as required by vertical and horizontal adjustments of the side mounts.

I claim:

1. In an inboard-outboard marine drive system including an engine, drive shaft assembly, transom plate assembly and outdrive unit, an improved engine mounting arrangement comprising:

a cylindrical drive shaft housing attached to and extending aft of an engine and an aft engine mount assembly attached to and carried by said housing,

said cylindrical housing having an annular step,

said aft mount assembly including an annular elastomeric sealing and vibration absorbing element disposed around and upon said housing with one side abutting said step, and

means movably attached to said housing and abutting the other side of said annular elastomeric element for axially compressing said element against said step and thereby radially expanding said element into radial compression between said housing and said transom plate assembly,

said transom plate assembly including a transom plate having a cylindrical passage therein, said passage having an end opening to the engine side of said transom plate, said cylindrical passage being adapted to axially receive therein through said open end said entire aft mount assembly, so that said entire mount assembly may be thrust into said passage through said open end and secured at various selected positions within said cylindrical passage.

2. The device of claim 1 wherein said step comprises an annular axially extending portion of said cylindrical housing having a reduced radius,

and wherein said means for axially compressing said elastomeric element includes an annular member adapted to ride partially over said axial portion and means for urging said annular member against the after end of said housing and said elastomeric element.

3. The device of claim 2 wherein said transom plate member includes abutment means cooperating with said aft mount assembly for limiting the penetration of said housing and mount within said cylindrical passage and for axially positioning said engine for attachment to said outdrive unit.

4. The device of claim 3 further including bi-axially adjustable engine mounts attached at selected points on each side of the engine and adapted for attachment to the bottom hull structure of a boat.

5. The device of claim 2 further including a bearing for the system drive shaft assembly and means for mounting said bearing inside of said drive shaft housing, including annular abutment means inside said cylindrical housing adapted to seat one side of said bearing and wherein said annular compressing member comprises a movable seat for the other side of said 

1. In an inboard-outboard marine drive system including an engine, drive shaft assembly, transom plate assembly and outdrive unit, an improved engine mounting arrangement comprising: a cylindrical drive shaft housing attached to and extending aft of an engine and an aft engine mount assembly attached to and carried by said housing, said cylindrical housing having an annular step, said aft mount assembly including an annular elastomeric sealing and vibration absorbing element disposed around and upon said housing with one side abutting said step, and means movably attached to said housing and abutting the other side of said annular elastomeric element for axially compressing said element against said step and thereby radially expanding said element into radial compression between said housing and said transom plate assembly, said transom plate assembly including a transom plate having a cylindrical passage therein, said passage having an end opening to the engine side of said transom plate, said cylindrical passage being adapted to axially receive therein through said open end said entire aft mount assembly, so that said entire mount assembly may be thrust into said passage through said open end and secured at various selected positions within said cylindrical passage.
 2. The device of claim 1 wherein said step comprises an annular axially extending portion of said cylindrical housing having a reduced radius, and wherein said means for axially compressing said elastomeric element includes an annular member adapted to ride partially over said axial portion and means for urging said annular member against the after end of said housing and said elastomeric element.
 3. The device of claim 2 wherein said transom plate member includes abutment means cooperating with said aft mount assembly for limiting the penetration of said housing and mount within said cylindrical passage and for axially positioning said engine for attachment to said outdrive unit.
 4. The device of claim 3 further including bi-axially adjustable engine mounts attached at selected points on each side of the engine and adapted for attachment to the bottom hull structure of a boat.
 5. The device of claim 2 further including a bearing for the system drive shaft assembly and means for mounting said bearing inside of said drive shaft housing, including annular abutment means inside said cylindrical housing adapted to seat one side of said bearing and wherein said annular compressing member comprises a movable seat for the other side of said bearing. 